1. Field of the Invention
The present invention relates to a method and an apparatus for examining a position of at least one board-support pin which is positioned on a board-support base for supporting a printed-circuit board under a back surface thereof, and a method and an apparatus for positioning at least one board-support pin on a board-support base.
2. Related Art Statement
It is widely practiced to produce an electric circuit by mounting electric components (ECs, e.g., electronic components) on a printed-circuit board (PCB). When the ECs are mounted on the PCB, at least one support member is used to support the PCB under a back surface thereof so as to prevent the PCB from sagging down. In the case where one or more ECs have already been mounted on the back surface of the PCB, the PCB can be supported at only limited portions of the back surface of the PCB. In this case, the PCB is supported, under the back surface thereof, by a free end of at least one board-support pin. To support the PCB at one or more limited portions of the back surface of the PCB, it is required to position the board-support pin at an arbitrary position on a board-support base. There is known a board supporting device which can do it.
However, if the position of the board-support pin positioned on the board-support base by the board supporting device is not appropriate, the board-support pin may support the PCB at a portion of the back surface of the PCB on which one or more ECs have been mounted. The inappropriate positioning of the board-support pin may cause a problem that the board-support pin interferes with at least one EC mounted on the back surface of the PCB. Therefore, it is needed to examine whether the actual position of the board-support pin is appropriate or not, after the board-support pin is positioned on the board-support base. Conventionally, this examination is done by an operator. Accordingly, the examination takes a lot of time, and cannot enjoy high accuracy.
It is therefore an object of the present invention to provide a method and an apparatus for speedily and reliably examining whether a position of at least one board-support pin on a board-support base is appropriate.
The present invention provides a method and an apparatus for examining a position of at least one board-support pin on a board-support base, and a method and an apparatus for positioning at least one board-support pin on a board-support base which respectively include the aforesaid method and apparatus for examining a position of the board-support pin. The invention methods and apparatuses have one or more of technical features which are described below in respective paragraphs given parenthesized sequential numbers (1) to (21). Any technical feature which includes another technical feature shall do so by referring, at the beginning, to the parentiesized sequential number given to the technical feature. Thus, two or more of the following technical features may be combined, if appropriate. Each technical feature may be accompanied by a supplemental explanation, as needed.
(1) According to a first feature of the present invention, there is provided a method of examining a position of at least one board-support pin which is positioned on a board-support base for supporting a printed-circuit board under a back surface thereof, the method comprising the steps of: taking an image of the board-support pin, at a position opposed to a free end of the pin; judging whether the position of the board-support pin is appropriate, based on the taken image; and producing judgment information indicative of a result of the judgment. In the present method, the position of the board-support pin is detected by taking the image of the board-support pin, the judgment of whether the position of the board-support pin is appropriate is automatically made, and the judgment information indicative of the result of the judgment is produced. The examination according to the present method is done more speedily and more accurately in comparison with a case where an operator examines the position of the board-support pin. As described below, the judgment information may be displayed on a display device so that the operator can recognize the result of the judgment, and/or may be supplied to a pin-position correcting device so that the pin-position correcting device automatically corrects the position of the board-support pin.
(2) According to a second feature of the present invention which includes the first feature (1), the method further comprises a step of displaying the judgment information on a display device so that an operator recognizes the judgment information. According to the judgment information displayed on the display device, the operator can recognize that the board-support pin is positioned at an inappropriate position, and correct the inappropriate position of the board-support pin. The judgment information may include the direction and amount of dislocation of the inappropriate position of the board-support pin from a reference position of the pin, in addition to the result of the judgment. In accordance with the judgment information displayed on the display device, the operator can more easily correct the inappropriate position of the board-support pin.
(3) According to a third feature of the present invention which includes the first or second feature (1) or (2), the method further comprises a step of supplying the judgment information to a pin-position correcting device so that the pin-position correcting device automatically corrects the position of the board-support pin, based on the judgment information. In this case, the inappropriate position of the board-support pin is automatically corrected by the pin-position correcting device, whereby the operator""s load is further reduced.
(4) According to a fourth feature of the present invention which includes any one of the first to third features (1) to (3), the step of taking the image of the board-support pin comprises taking the image of the board-support pin, with an image taking device which is for taking an image of each of a plurality of reference board marks provided on the printed-circuit board so as to detect a position of the printed-circuit board. In the present method, the image taking device is used for taking the image of the board-support pin in addition to the image of each of the reference board marks. Thus, the present method can be performed using an apparatus which can be produced at low cost. Generally, a plurality of reference board marks are provided at a plurality of positions being apart from one another on a PCB, so that the position of the PCB may be accurately detected. Similarly, a plurality of board-support pins may be positioned at a plurality of positions being apart from one another on the board-support base. Therefore, it is needed to move the image taking device relative to the PCB in a direction parallel to the PCB. Since the image taking device is used for taking both the image of the board-support pin and the image of each of the reference board marks, a single moving device for moving one of the image taking device and the PCB relative to the other of the image taking device and the PCB can also be used for taking both of the images. The use of the single moving device further reduces the production cost of the apparatus.
(5) According to a fifth feature of the present invention which includes any one of the first to fourth features (1) to (4), a reference pin mark is provided on a free-end surface of the board-support pin, the free-end surface provides a board-support surface for supporting the printed-circuit board, and the step of taking the image of the board-support pin comprises taking an image of the reference pin mark. In the case where the free-end surface of the board-support pin is relatively small, an image of the free-end surface itself may be taken as the image of the board-support pin. On the other hand, in the case where the free-end surface of the pin is relatively large, it is preferable that an image of a reference pin mark provided on the free-end surface be taken as the image of the board-support pin. Generally, as the area of the image taken by the image taking device decreases, the accuracy of detection of the pin position improves. On the other hand, generally, the accuracy of positioning of the board-support pin is relatively low. Even if the image area may be decreased, it is required that an object whose image is taken by the image taking device fall within the image area. Therefore, it is preferable to take an image of the reference pin mark which is smaller than the free-end surface of the board-support pin. Specifically, in the case where the image taking device for taking the image of each of the reference board marks is used for taking the image of the board-support pin, it is not recommended to widen the image area of the image taking device to be able to take an image of the relatively large free-end surface of the board-support pin. Since each of the reference board marks is relatively small, the widening of the image area may deteriorate the accuracy of detection of the position of the each reference board mark.
(6) According to a sixth feature of the invention. which includes the fifth feature (5), a hole is formed in the board-support pin so as to open in the free-end surface of the pin, and the reference pin mark comprises the opening of the hole. Since the hole opens in the free-end surface of the board-support pin, there is a difference in brightness between the image of the opening of the hole and the image of the free-end surface. Accordingly, it is possible to employ the opening of the hole as the reference pin mark. If the hole is formed through the board-support pin in its axial direction, the air sucked into the hole from the free-end surface of the pin can be ejected from a bottom surface of the board-support pin. In this case when the bottom surface of the pin contacts the board-support base, the ejected air blows off dust or the like present on a portion of the board-support base on which the pin is to be positioned.
(7) According to a seventh feature of the present invention which includes any one of the first to sixth features (1) to (6), the step of judging whether the position of the board-support pin is appropriate comprises comparing the taken image with reference-pin-position information indicative of a reference position of the pin. For example, the reference-pin-position information may be a reference image of the pin positioned at its reference position, or a set of pin-position data indicative of the reference position of the pin on an X-Y coordinate plane. In the case where the reference image is employed as the reference-pin-position information, the taken image of the pin is directly compared with the reference image. On the other hand, in the case where the set of pin-position data (i.e., the reference X and Y coordinates) is employed as the reference-pin-position information, the actual X and Y coordinates of the board-support pin on the X-Y coordinate plane are calculated based on the taken image of the pin, and then the actual coordinates are compared with the reference X and Y coordinates. In both cases, it is judged that the position of the board-support pin is appropriate when respective errors of the actual X and Y coordinates of the pin from the reference X and Y coordinates of the pin fall within a predetermined range.
(8) According to an eighth feature of the present invention which includes any one of the first to sixth features (1) to (6), the step of judging whether the position of the board-support pin is appropriate comprises comparing the taken image with reference-component-position information indicative of a reference position of at least one electric component mounted on the back surface of the printed-circuit board. For example, a safety region is set around the reference image of the free-end surface of the board-support pin, based on errors produced when the image of the pin is taken, and/or errors produced when the EC is mounted on the PCB. It is judged that the position of the board-support pin is appropriate, if the safety region does not overlap the reference position of the EC mounted on the back surface of the PCB. In the present method, whether a template or at least one set of predetermined data which defines at least one reference position is appropriate is also examined.
(9) According to a ninth feature of the present invention, there is provided a method of positioning at least one board-support pin on a board-support base for supporting a printed-circuit board under a back surface thereof, the method comprising the steps of positioning the at least one board-support pin on the board-support base according to at least one reference position defined by a template which is located above the board-support base, the template having a pin-position standard which defines the reference position, taking an image of the board-support pin, at a position opposed to a free end of the pin, judging whether the position of the board-support pin is appropriate, based on the taken image, and producing judgment information indicative of a result of the judgment.
(10) According to a tenth feature of the present invention which includes the ninth feature (9), the step of positioning the board-support pin on the board-support base comprises fixing the pin to the base by utilizing a magnetic attraction force produced by an electromagnet.
(11) According to an eleventh feature of the present invention, there is provided a method of positioning at least one board-support pin on a board-support base for supporting a printed-circuit board under a back surface thereof, the method comprising the steps of automatically positioning, with a pin positioning device, the at least one board-support pin on the board-support base, based on at least one set of predetermined data; and examining a position of the board-support pin by taking an image of the pin, at a position opposed to a free end of the pin, judging whether the position of the board-support pin is appropriate, based on the taken image, and producing judgment information indicative of a result of the judgment. In the present method, the board-support pin is automatically positioned on the board-support base, whereby the operator""s load is more reduced. The step of automatically positioning the board-support pin may be performed independent of the step of examining the position of the board-support pin.
(12) According to a twelfth feature of the present invention which includes the eleventh feature (11), the method further comprises a step of correcting the position of the board-support pin, based on the produced judgment information. The step of correcting the position of the board-support pin may be performed independent of the step of examining the position of the board-support pin.
(13) According to a thirteenth feature of the present invention which includes the twelfth feature (12), the step of correcting the position of the board-support pin comprises correcting the position of the board-support pin, with the pin positioning device. The correction of position of the board-support pin is automatically performed by the pin positioning device, whereby the operator""s load is more reduced.
(14) According to a fourteenth feature of the present invention which includes any one of the eleventh to thirteenth features (11) to (13), the step of positioning the board-support pin on the board-support base comprises fixing the pin to the base by utilizing a magnetic attraction force produced by an electromagnet. By controlling the energizating and deenergization of the electromagnet to produce or cut the magnetic attraction force, the board-support pin is easily attached to, or detached from, the board-support base. More particularly, the step of positioning the board-support pin on the board-support base or the step of correcting the position of the board-support pin is easily performed. The step of fixing the pin to the base may be performed independent of the step of examining the position of the board-support pin.
(15) According to a fifteenth feature of the present invention, there is provided an apparatus for examining a position of at least one board-support pin which is positioned on a board-support base for supporting a printed-circuit board under a back surface thereof, the apparatus comprising: an image taking device which takes an image of the board-support pin, at a position opposed to a free end of the pin; a moving device which moves at least one of the image taking device and the board-support base relative to the other of the image taking device and the board-support base in a direction parallel to the board-support base; a first controller which controls the moving device such that the image taking device is positioned at the position opposed to the free end of the board-support pin; and a judging device which judges whether the position of the board-support pin is appropriate, based on the image taken by the image taking device, and which produces judgment information indicative of a result of the judgment. The present apparatus advantageously performs the method of examining a position of at least one board-support pin.
(16) According to a sixteenth feature of the present invention which includes the fifteenth feature (15), the apparatus further comprises a second controller which controls the moving device such that the image taking device is positioned at each of a plurality of positions respectively opposed to a plurality of reference board marks provided on the printed-circuit board.
(17) According to a seventeenth feature of the present invention, there is provided an apparatus for positioning at least one board-support pin on a board-support base for supporting a printed-circuit board under a back surface thereof, the apparatus comprising: a pin fixing device which fixes the board-support pin to the board-support base; an image taking device which takes an image of the board-support pin at a position opposed to a free end of the pin fixed to the board-support base by the pin fixing device; a moving device which moves at least one of the image taking device and the board-support base relative to the other of the image taking device and the board-support base in a direction parallel to the board-support base; a controller which controls the moving device such that the image taking device is positioned at the position opposed to the free end of the board-support pin; and a judging device which judges whether the position of the board-support pin is appropriate, based on the image taken by the image taking device, and which produces judgment information indicative of a result of the judgment. The present apparatus advantageously performs the method of positioning at least one board-support pin on a board-support base.
(18) According to an eighteenth feature of the present invention which includes the seventeenth feature (17), the apparatus further comprises a pin-position defining device which defines at least one reference position.
(19) According to a nineteenth feature of the present invention which includes the eighteenth feature (18), the pin-position defining device comprises a template which defines the at least one reference position.
(20) According to a twentieth feature of the present invention which includes the eighteenth or nineteenth feature (18) or (19), the pin-position defining device comprises a memory which stores at least one set of pin-position data indicative of the at least one reference position.
(21) According to a twenty-first feature of the present invention which includes the twentieth feature (20), the apparatus further comprises a pin positioning device which positions, on the board-support base, the board-support pin at the reference position indicated by the set of pin-position data.